From: Logan Capaldo <logancapaldo@...>
Date: 2005-06-10T20:35:56+09:00
Subject: Re: [RFC] framework of Ruby/Tk + VNC

On 6/9/05, Hidetoshi NAGAI <nagai@ai.kyutech.ac.jp> wrote:
> Hi,
> 
> I'm working on a framework of Ruby/Tk + VNC.
> Its purpose is to put GUI applications of Ruby/Tk on internet view.
> The concept of the framework is,
> 
>  * Use VNC (RFB protocol)
> 
>  * A GUI application is running on a safe (safe-Tk) based
>    slave interpreter (usually, $SAFE == 4).
>    If required, you can also use a non-safe based slave.
> 
>  * Never use general window managers to decrease security risk.
>    Except a VNC server, only one Ruby/Tk process is running.
>    # In the future, it may be expected that Ruby/Tk has
>    # RFB server functions and no VNC server is required
>    # for this purpose.
> 
>  * A canvas widget of the master interpreter works like
>    as a window manager. The canvas widget administers the
>    slave interpreter's root/toplevel widgets by window items
>    embedded them.
> 
> By comparison with using tclplugin, probably, the followings
> are advantages.
> 
>  * If the user already has a kind of VNC viewer,
>    he can use it to access the application.
> 
>  * When the user access the application by a web browser,
>    the application server can send a JAVA viewer applet.
>    Therefore, the user doesn't need to install any plugins.
> 
>  * Even if the application uses some Tcl/Tk extensions,
>    the user doesn't need to install such extensions.
> 
>  * No need to send the source of the application.
>    Funcamentally, interchanged data are only window events
>    and display images on RFB protocol.
>    So, it can decrease the cost of care for security.
> 
> Disadvantages are,
> 
>  * Slow, because it is remote access through networks.
> 
>  * Much resources are required on the server.
> 
> A sample script based on this concept is attached
> at the end of this mail.
> That requires 2005/06/08 or later version of Ruby.
> Please note that, because of using multi-tk library,
> the description of script on the slave interpreter is
> almost same as the description of usual Ruby/Tk script.
> 
> Although it is an old and slow machine and is not
> decided how long term it is available to use,
> there is a server to try the sample script.
> Please access 131.206.154.81:33 by VNC viewer,
> or http://131.206.154.81/ by web browser.
> Of course, Ruby is not required on user's machine.
> 
> # When by a web browser, a dialog to require password is shown.
> # Please ignore it and press the "OK" button with empty password.
> 
> Any comments (or wish to participate in the development ;-))
> are welcome.
> 
>                       Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)
> 
 

Neat! Once upon a time I read up on the RFB protocol, I don't believe
it would be too difficult to make a Tk/RFB server assuming Tk's
drawing and input layers are abstracted (which I am sure they are
since it is so portable).